Electronic – Problem with a nixie clock

clockkitsnixie

I bought this nixie clock kit and it is partially working. One of the issues I'm having is that the 6th hour does not light up so if the clock is at 06:00:00 to 06:59:59 the 6 will not light up for the duration of the hour. At one point after fiddling around with the positioning of the tubes, it is the 9th hour that has this problem. The 6 (and the 9 at one point) works in the minutes and seconds. No it is not the tubes.

The other issue is that the time starts lagging by a second every other day.

I've followed the instructions and built the kit but I'm not too well-versed in electrical components. What exactly is controlling the time functionalities? I am thinking it is software related and thought it was the MOSFETS IC2 and IC3 that controlled it but apparently all the MOSFETS do is regulate the voltage… I may have dropped the IC2 MOSFET at one point and thought that it may have been damaged which caused this abnormal behaviour but since it only controls the voltage, that can't be it…

I have contacted the seller but he is not offering much help. If any one have experience with nixie clocks or this kit in particular, any help/pointers/advice would be greatly appreciated.

Best Answer

The manual says that booster generates 170V DC, when datasheet for IC HV5812 specced for 90V absolute max. The driver IC is killed by design. There is no means in booster schematics to limit the voltage to any predictable value (no zener of voltage feedback).

Old russian equivalent driver K155id1 is BJT based and specced to 60V max, but has a voltage limiting zener per each output 0.5 mA max, so it could survive better. Possibly the replacement with contemporary device was done with mistake of not adding a single 80V zener to booster.